code: def combine_column_order(df_1, df_2, both_cols=None):
      """Determine the sort order for the combined columns of two DataFrames
  
      Parameters
      ----------
      df_1: pd.DataFrame
          The first DataFrame, whose columns will be sorted. Columns unique to `df_1` will be sorted
          before those of `df_2`
      df_2: pd.DataFrame
          The second DataFrame, whose columns will be sorted. Columns unique to `df_2` will be sorted
          after those of `df_1`
      both_cols: list, or None, default=None
          If list, the column names that should be common to both DataFrames and placed last in the
          sort order
  
      Returns
      -------
      combined_cols: list of strings
          The result of combining and sorting column names from `df_1`, and `df_2`
  
      Examples
      --------
      >>> df_1 = pd.DataFrame(columns=['A', 'B', 'C', 'Common_1', 'Common_2'])
      >>> df_2 = pd.DataFrame(columns=['A', 'D', 'E', 'Common_1', 'Common_2'])
      >>> combine_column_order(df_1, df_2, both_cols=['Common_1', 'Common_2'])
      ['A', 'B', 'C', 'D', 'E', 'Common_1', 'Common_2']
      >>> combine_column_order(df_1, df_2, both_cols=None)
      ['A', 'Common_1', 'Common_2', 'B', 'C', 'D', 'E']
      """
      both_cols = both_cols or []
      df_1_cols = [_ for _ in list(df_1.columns) if _ not in both_cols]
      df_2_cols = [_ for _ in list(df_2.columns) if _ not in both_cols]
  
      common_cols = [_ for _ in df_1_cols if _ in df_2_cols]
      unique_cols_1 = [_ for _ in df_1_cols if _ not in df_2_cols]
      unique_cols_2 = [_ for _ in df_2_cols if _ not in df_1_cols]
  
      combined_cols = (
          common_cols + unique_cols_1 + unique_cols_2 + both_cols
      )
      return combined_cols
  
file_path: hyperparameter_hunter/hyperparameter_hunter/i_o/leaderboards.py
imports: from abc import ABCMeta, abstractmethod
  from collections import OrderedDict
  from numbers import Number
  import numpy
  import pandas
  from typing import Dict, List, Optional, Tuple
label_desc: Use image node_id 2 for calling a global function with example usage: combine_column_order(df_1, df_2, both_cols) and returns: combined_cols